Respiratory Virus Pneumonia after Hematopoietic Cell Transplantation (HCT): Associations between Viral Load in Bronchoalveolar Lavage Samples, Viral RNA Detection in Serum Samples, and Clinical Outcomes of HCT

Background. Few data exist on respiratory virus quantitation in lower respiratory samples and detection in serum from hematopoietic cell transplant (HCT) recipients with respiratory virus-associated pneumonia. Methods. We retrospectively identified HCT recipients with respiratory syncytial virus (RSV), parainfluenza virus, influenza virus, metapneumovirus (MPV), and coronavirus (CoV) detected in bronchoalveolar lavage (BAL) samples, and we tested stored BAL and/or serum samples by quantitative polymerase chain reaction. Results. In 85 BAL samples from 82 patients, median viral loads were as follows: for RSV (n=35), 2.6×10(6) copies/mL; for parainfluenza virus (n=35), 4.9×10(7) copies/mL; for influenza virus (n=9), 6.8×10(5) copies/mL; for MPV (n=7), 3.9×10(7) copies/mL; and for CoV (n=4), 1.8×105 copies/mL. Quantitative viral load was not associated with mechanical ventilation or death. Viral RNA was detected in serum samples from 6 of 66 patients: 4 of 41 with RSV pneumonia, 1 with influenza B, and 1 with MPV/influenza A virus/CoV coinfection (influenza A virus and MPV RNA detected). RSV detection in serum was associated with high viral load in BAL samples (P=.05), and viral RNA detection in serum was significantly associated with death (adjusted rate ratio, 1.8; P=.02). Conclusion. Quantitative polymerase chain reaction detects high viral loads in BAL samples from HCT recipients with respiratory virus pneumonia. Viral RNA is also detectable in the serum of patients with RSV, influenza, and MPV pneumonia and may correlate with the severity of disease.